The present invention relates to letter input methods and devices and, more particularly, to small-size Japanese letter input devices for portable terminals.
Among usual letter input means are keyboards with key top impression of alphabets, numerals, Japanese kana letters, etc. and also ten key sets used for portable telephone sets or the like.
Among other typical letter input devices are touch panels. A touch panel is a letter input device for inputting position data corresponding to its touched spot. This device has an integral display with a keyboard display thereon. By touching the keyboard display at spot thereof, corresponding letter data is inputted.
Japanese Patent Laid-Open No. 63-58590 entitled “Vector Pattern Input Device” discloses a character input device using a touch panel. In this device, characters are inputted by recognizing them from strokes drawn on the touch panel.
Japanese Patent Laid-Open No. 6-161433 entitled “Electronic Musical Instrument with Letter Input Function” discloses a device using a rotary dial, which is rotatable for displaying letters on a display. In this device, Letters are inputted when they are displayed. This device has a set selection switch for selecting a numeral set and a large and a small alphabet letter set. The large and small letter sets are selected by depressing the switch.
Japanese Patent Laid-Open No. 7-129294 entitled “Letter Input Device” discloses a letter input device, which permits inputting letters with a single hand. To this end, the device comprises a frame, which is of such a size that it can be gripped with a single hand and has a rotor capable of being rotated with the thumb and a key switch operable with a finger other than the thumb. In this device, letters are inputted by deducing a vowel row from a detected angle of rotation of a rotary bar and deducing a consonant column from a detected state of depression of a key switch.
Japanese Patent Laid-Open No. 7-168658 entitled “Letter Input Device and Method” discloses input of letters by using a track pole and a set of step-wise depression adjustment switches. In this case, four switches capable of detecting five depression steps are used to determine letters to be inputted, and a track pole is used to cause movement of a cursor displayed on a display. In this way, the input of letters and the cursor operation are permitted.
Japanese Patent Laid-open No. 6-202807 entitled “Letter Input/Display Device” discloses an input device using a mouse. In the device, a table of letters is partly displayed on a display for scrolling by moving a mouse. When a desired letter appears, it can be inputted by clicking the mouse.
Japanese Patent Laid-Open No. 6-131095 entitled “Japanese Kana Letter Input System Based on Pointing Device” discloses combined use of a pointing device and a push button switch having a single button capable of being depressed in a plurality of different steps. In this case, certain steps of depression of the button are allotted to the consonant mark and p-sound mark of Japanese kana letters. The input of Japanese kana letters is thus simplified by the combination of the 50-letter set displayed on a display and the button.
Japanese Patent Laid-Open No. 5-341903 entitled “Letter Information Input Device” discloses simplified letter input. In this case, a tablet is used, and a keyboard display is made on a display. In this letter information input device, a letter is not inputted absolutely by pointing a position on the display. Instead, the letter is inputted according to position relative to the pointed position, that is, touch feel letter input is possible without reference to the display.
The above first-mentioned case of letter input by using a usual keyboard, has the following problems. Where romaji letters are inputted with a keyboard, at least 26 letter keys are necessary in addition to a large/small letter size switch key and numeral keys, that is, a total of at least 40 keys are necessary.
In addition, where these keys are to be depressed with fingers, the size of each of key in the set can not be made smaller than is necessary for being depressed with a finger. Thus, a large area is required as a whole.
This input method poses no problem in the case of a relatively large device used on a desk, such as a desk top personal computer or a note personal computer. However, in relatively small portable terminals such as PDAs (personal digital assistants), it is not so realistic to mount a keyboard. Besides, in the case of a PDA or like terminal which is relatively frequently held and used with a single hand rather than being put on a desk, it is extremely difficult to input letters with a keyboard.
The above second case, in which a touch panel is used for letter recognition, has the following problems. In a small-size device such as a portable telephone set or like portable terminal, if it is intended to secure a hand-written letter input area for letter recognition, the display area of the screen is reduced, thus making it difficult to input a sentence. In addition, for inputting letters it is necessary to use in combination a pen or like relatively thin input device with a pointed tip. This means that a pen or the like should always be carried and be taken out whenever letter data is to be inputted. Moreover, in such a situation it is necessary to use the pen while holding the device body with one hand. That is, it is necessary to hold the pen with one hand while holding the body with the other hand. Both hands are thus occupied.
The above third-mentioned case, which is an electronic musical instrument with a letter input function and having a dial for selecting letters and also a set selection switch for selecting a small or a large letter set, has the following problem. For detecting a letter on the diametrically opposite dial side of a presently selected letter, i.e., 180-degree out-of-phase therefrom, a number of finger operations are necessary. It is thus difficult to continuously input a large number of letters.
The above fourth-mentioned letter input device has the following problems. In this case, a rotor is used to deduce vowel rows, and a key switch is used to deduce consonant columns. However, it is difficult to determine by the sense of feel the rotation angle of the rotor corresponding to a vowel row to be selected. Also, it is difficult to determine by feel the number of times of depression of the key switch corresponding to a desired consonant column to be selected. For letter selection, it is thus necessary such means that all the letters capable of being selected are always displayed on a display for selecting letters with reference to the display. Such a display of letters, however, requires a corresponding display area. This means that it is difficult to input letters by viewing a sentence. Besides, since letters are inputted with two different kinds of switches, i.e., the rotor and a see-saw switch, it is impossible to input letters with a single finger.
The above fifth-mentioned case of letter input, i.e., the letter input device and method using a plurality of step-wise depression adjustment switches for the letter input, has the following problems. In this case, positions of one of the switches which can be depressed step-wise is allotted to the vowels, and positions of the other switches are allotted to the consonants. This dictates the user to memorize the vowels and consonants corresponding to the respective switch positions. However, it is rather difficult for the user to memorize these switch positions. In addition, the switches are adapted to produce clicks when they are depressed step-wise to the individual positions, and thus can be readily depressed to desired positions. However, since a plurality of switches are provided, their depression forces adjustment at a time is difficult.
The above sixth-mentioned case, i.e., the letter input/display device, in which the 50-letter set is displayed on a display for scrolling, and a desired letter is inputted with a determining button switch when it appears, has the following problem. In this case of letter input the display should be scrolled at a high speed such as on a display unit of a personal compute CRT monitor. However, in the case of a liquid crystal display in a portable terminal or the like, such scrolling makes it difficult to recognize the display and frequently makes it substantially impossible to select letters.
The above seventh-mentioned case, i.e., the Japanese kana letter input system based on pointing device, has a problem that a Japanese kana letter set should be displayed on a display. In a portable terminal or the like, the display area of the screen is too small to be able to display the kana letter set, or if such display is possible, the size of the individual displayed letters is extremely small. This means that it is difficult to select letters.
The above eighth-mentioned case, i.e., the letter information input device, is applicable to devices without need of portability considerations. A problem in this case resides in the use of a tablet independently of the display screen for the letter input. The tablet requires an extra space, and is therefore unsuited to the cases concerning the portability.